U.S. patent application number 10/231153 was filed with the patent office on 2004-03-04 for diagnostic apparatus for gas mixture supply apparatus and diagnostic method thereof.
This patent application is currently assigned to Hitachi, Ltd.. Invention is credited to Amou, Kiyoshi, Ichihara, Takanobu, Someno, Tadashi.
Application Number | 20040040550 10/231153 |
Document ID | / |
Family ID | 19088347 |
Filed Date | 2004-03-04 |
United States Patent
Application |
20040040550 |
Kind Code |
A1 |
Someno, Tadashi ; et
al. |
March 4, 2004 |
DIAGNOSTIC APPARATUS FOR GAS MIXTURE SUPPLY APPARATUS AND
DIAGNOSTIC METHOD THEREOF
Abstract
A diagnostic apparatus for gas mixture supply apparatus and
diagnostic method thereof characterized in that, when any trouble
has occurred to gas mixture from a gas mixture supply apparatus, it
can be identified as an error; and at least engine startup is
ensured, continued operation of the engine can be made enabled
without any problem which may cause stalling of the engine, and
deterioration of exhaust gas can be prevented. The above object can
be attained by the present invention comprising a gas mixture state
detecting means for detecting the state of gas mixture when gas
mixture is supplied from the aforementioned gas mixture supply
means during the operation of the aforementioned evaporation means,
and evaluation means for evaluating an error of the aforementioned
gas mixture supply means based on the result of detection by the
aforementioned gas mixture state detecting means.
Inventors: |
Someno, Tadashi;
(Hitachinaka, JP) ; Amou, Kiyoshi; (Chiyoda,
JP) ; Ichihara, Takanobu; (Hitachinaka, JP) |
Correspondence
Address: |
CROWELL & MORING LLP
INTELLECTUAL PROPERTY GROUP
P.O. BOX 14300
WASHINGTON
DC
20044-4300
US
|
Assignee: |
Hitachi, Ltd.
Hitachi Car Engineering Co., Ltd.
|
Family ID: |
19088347 |
Appl. No.: |
10/231153 |
Filed: |
August 30, 2002 |
Current U.S.
Class: |
123/704 ;
123/478; 123/549; 123/590 |
Current CPC
Class: |
F02M 31/18 20130101;
F02D 41/0037 20130101; F02M 69/044 20130101; F02D 41/3094 20130101;
F02D 37/02 20130101; Y02T 10/12 20130101; F02D 41/221 20130101;
Y02T 10/126 20130101 |
Class at
Publication: |
123/704 ;
123/549; 123/478; 123/590 |
International
Class: |
F02M 051/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2002 |
JP |
2001-261277 |
Claims
What is claimed:
1. In a gas mixture supply apparatus of an internal combustion
engine comprising; a main fuel injection valve for supplying fuel
to an internal combustion engine, an upstream fuel injection valve
for supplying fuel to the area upstream from said main fuel
injection valve, and gas mixture supply means for supplying gas
mixture from upstream of said main fuel injection valve through an
evaporation means for evaporating all or part of fuel supplied from
said upstream fuel injection valve; a diagnostic apparatus for said
gas mixture supply apparatus comprising; gas mixture state
detecting means for detecting the state of gas mixture when gas
mixture is supplied from said gas mixture supply means with said
evaporation means operating, and evaluation means for evaluating an
error of said gas mixture supply means based on the result of
detecting said gas mixture state detecting means.
2. In a gas mixture supply apparatus of an internal combustion
engine for supplying gas mixture from the area upstream of said
main fuel injection valve utilizing; a main fuel injection valve
for supplying fuel to an internal combustion engine, an upstream
fuel injection valve for supplying fuel to the area upstream from
said main fuel injection valve, a heater member for heating all or
part of fuel supplied from said upstream fuel injection valve and
evaporating it, and heater control means for controlling
application of electric power to said heater member; a diagnostic
apparatus for a gas mixture supply apparatus comprising; gas
mixture state detecting means for detecting the state of gas
mixture formed when fuel is supplied from said upstream fuel
injection valve with electric power applied to said heater member
by said heater control means, and evaluation means for evaluating
an error of said upstream fuel injection valve and/or said heater
member based on the result of detecting said gas mixture state
detecting means.
3. A diagnostic apparatus for a gas mixture supply apparatus
according to claim 1 or 2 further characterized in that said gas
mixture state detecting means detects the state of gas mixture
based on the result of detecting at least one of engine speed,
intake manifold pressure, combustion pressure, torque value,
exhaust temperature, HC concentration, NOx concentration and CO
concentration.
4. A diagnostic apparatus for a gas mixture supply apparatus
according to any one of claims 1 through 3 further characterized in
that evaluation is made by said evaluation means based on at least
one of the absolute value of the result of detecting said gas
mixture state detecting means, the amount and rate of change,
deviation from a predetermined target value and fluctuating
surge.
5. A diagnostic apparatus for a gas mixture supply apparatus
according to claim 1 characterized by further comprising; fail-safe
control means containing; a step of reducing the amount of fuel or
stopping the supply of fuel in response to the evaluation made by
said evaluation means as containing an error, a step of increasing
the amount of fuel supplied from said main fuel injection valve or
switching to said main fuel injection valve, a step of stopping
said evaporation means, and a step of correcting ignition timing;
wherein said fail-safe control means is used in such a way as to
reduce deterioration of the state of said internal combustion
engine operation and/or increase in the amount of hazardous exhaust
gas.
6. A diagnostic apparatus for a gas mixture supply apparatus
according to claim 2 characterized by further comprising; fail-safe
control means containing; a step of reducing the amount of fuel or
stopping the supply of fuel in response to the evaluation made by
said evaluation means as containing an error, a step of increasing
the amount of fuel supplied from said main fuel injection valve or
switching to said main fuel injection valve, a step of stopping
application of electric power to said heater member, and a step of
correcting ignition timing; wherein said fail-safe control means is
used in such a way as to reduce deterioration of the state of said
internal combustion engine operation and/or increase in the amount
of hazardous exhaust gas.
7. A diagnostic apparatus for a gas mixture supply apparatus
according to claim 1 characterized by further comprising; main fuel
supply evaluation means containing; a step of injecting fuel
through said main fuel injection valve at least during start
cranking, and a step of evaluating fuel supply as being normal
through said main injection valve when engine speed has exceeded a
predetermined level or intake manifold pressure has been reduced
below a predetermined level; and a fuel supply change means
containing; a step of reducing the amount of fuel or stopping the
supply of fuel in response to the evaluation made by said main fuel
supply evaluation means as being normal, a step of increasing the
amount of fuel supplied from said upstream fuel injection valve or
switching to said upstream fuel injection valve, and a step of
actuating said evaporation means.
8. A diagnostic apparatus for a gas mixture supply apparatus
according to claim 2 characterized by further comprising; main fuel
supply evaluation means containing; a step of injecting fuel
through said main fuel injection valve at least during start
cranking, and a step of evaluating fuel supply as being normal
through said main injection valve when engine speed has exceeded a
predetermined level or intake manifold pressure has been reduced
below a predetermined level; and a fuel supply change means
containing; a step of reducing the amount of fuel or stopping the
supply of fuel in response to the evaluation made by said main fuel
supply evaluation means as being normal, a step of increasing the
amount of fuel supplied from said upstream fuel injection valve or
switching to said upstream fuel injection valve, and a step of
applying electric power to said heater member.
9. A diagnostic apparatus for a gas mixture supply apparatus
according to claim 1, 5 or 7 characterized by further comprising;
an auxiliary air passage for bypassing a throttle valve, an
auxiliary air passage valve for regulating the amount of air in
said auxiliary air passage, target speed control means for
controlling said auxiliary air passage valve to reach a
predetermined target speed after said internal combustion engine
has started and has been evaluated, ignition timing control means
for controlling ignition timing to be on the side of delay angle at
least when fuel is supplied from said upstream fuel injection
valve, and evaluation means for evaluating one or more errors in
said upstream fuel injection valve, said evaporation means, and
said auxiliary air passage valve, based on the result of detection
by said gas mixture state detecting means when said ignition timing
is controlled to be on the side of delay angle.
10. A diagnostic apparatus for a gas mixture supply apparatus
according to claim 2, 6 or 8 characterized by further comprising;
an auxiliary air passage for bypassing a throttle valve, an
auxiliary air passage valve for regulating the amount of air in
said auxiliary air passage, target speed control means for
controlling said auxiliary air passage valve to reach a
predetermined target speed after said internal combustion engine
has started and has been evaluated, ignition timing control means
for controlling ignition timing to be on the side of delay angle at
least when fuel is supplied from said upstream fuel injection
valve, evaluation means for evaluating one or more errors in said
upstream fuel injection valve, said heater member, and said
auxiliary air passage valve, based on the result of detection by
said gas mixture state detecting means when said ignition timing is
controlled to be on the side of delay angle.
11. A diagnostic apparatus for a gas mixture supply apparatus
according to claim 9 or 10 characterized in that said ignition
timing control means performs control of ignition timing in terms
of delay angle in a predetermined number of times.
12. A diagnostic apparatus for a gas mixture supply apparatus
according to claim 9 or 10 characterized in that said gas mixture
state detecting means detects the state of gas mixture based on the
result of detecting one or more of the amounts of sucked air,
auxiliary air passage valve control and fuel injection.
13. A diagnostic apparatus for a gas mixture supply apparatus
according to claim 1 characterized by comprising; means for
evaluating the deterioration of battery, and means for evaluating
said gas mixture supply means for an error based on the result of
detecting battery voltage when fuel is supplied from said upstream
fuel valve after evaluation is made to determine that a battery is
not deteriorated.
14. A diagnostic apparatus for a gas mixture supply apparatus
according to claim 2 characterized in that said gas mixture state
detecting means detects the state of gas mixture based on; the
result of detection by; heater current detecting means for
detecting the current applied to said heater member, and said
heater current detecting means subsequent to electric power to said
heater member having been applied to said heater member; and the
trouble setup value of a heater current to be set in conformity to
the amount of fuel injection in advance.
15. A diagnostic apparatus for a gas mixture supply apparatus
according to any one of claims 1, 3 and 13 characterized by
comprising error storage means for storing an error when such an
error has been found out by said evaluation means, and/or error
alarm means for alarming an error.
16. A diagnostic apparatus for a gas mixture supply apparatus
according to either claims 1 or 5 characterized in that said
evaporation means performs at least one of evaporation by an
electric heater, heater evaporation by combustion, evaporation by
ultrasonic vibration, evaporation by hot water and evaporation by
exhaust gas temperature.
17. A diagnostic method for gas mixture supply apparatus of an
internal combustion engine comprising; a main fuel injection valve
for supplying fuel to an internal combustion engine, an upstream
fuel injection valve for supplying fuel to the area upstream from
said main fuel injection valve, and gas mixture supply means for
supplying gas mixture from upstream of said main fuel injection
valve through an evaporation means for evaporating all or part of
fuel supplied from said upstream fuel injection valve; said
diagnostic method comprising; a step of detecting the state of gas
mixture when gas mixture is supplied from said gas mixture supply
means with said evaporation means operating, and a step of
evaluating an error of said gas mixture supply means based on the
said result of detection.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a diagnostic apparatus for
a gas mixture supply apparatus and diagnostic method thereof. More
particularly, it relates to a trouble diagnostic apparatus of the
gas mixture supply apparatus of an internal combustion engine
equipped with gas mixture supply means for supplying gas mixture
from upstream of the main fuel injection valve, a diagnostic method
thereof and improvement of fail-safe measures.
[0002] In the prior art proposal, fuel injected by a fuel injection
valve is heated and evaporated by a heater provided on an intake
passage, thereby reducing the amount of fuel deposited on the
intake passage and intake valve, and improving combustion at the
time of starting a freezer, in particular. It also proposes a
method for reducing the emission volume of hazardous hydrocarbon.
For example, U.S. Pat. No. 5,894,832 proposes that a fuel injection
valve (upstream fuel injection valve) and a heater are installed in
an auxiliary air passage for bypassing an upstream throttle valve
in addition to a fuel injection valve main fuel injection valve)
provided close to the intake port of each cylinder. This
configuration allows fuel to be injected from the upstream fuel
injection valve to the heater in the warm-up process after starting
the freezer, and prevents fuel from depositing on the intake
passage by fuel evaporation promoted by the heater, thereby
improving combustion.
[0003] According to the aforementioned known example, furthermore,
gas mixture formation is improved by supply of evaporated fuel into
the cylinder, with the result that combustion is improved.
Accordingly, stable combustion can be ensured even if the delay
angle for ignition timing in the idling operation after startup is
made greater than the conventional engine without heater. This
provides an advantage of reducing the amount of emitted hazardous
hydrocarbon (HC) after startup of the freezer, by heating and
evaporating fuel through a heater and increasing the delay angle
for ignition timing so that exhaust temperature is raised to
promote the activity of catalyst. The aforementioned known example
also discloses a method for evaluating an error by heater current
value when the data current detecting means is provided.
[0004] Japanese Application Patent Laid-Open Publication Nos.
2000-213398 and 2000-274296 disclose a method for improving
combustion in the area of high speed and high load especially
through homogenous air intake in a direct injection spark ignition
type internal combustion engine, alternating current they are not
directly intended to improve of combustion at the time of freezer
startup. Namely, they disclose a fuel injection control apparatus
provided with switching control means to ensure that fuel supply
function is shared between the main fuel injection valve for
direction injection of fuel into a combustion chamber and an
auxiliary fuel injection valve capable of supplying fuel in the
intake passage, wherein they propose means for diagnosing a trouble
of the auxiliary fuel injection valve based on a predetermined
operation condition--an air-fuel ratio detected in the area of high
speed and high load, according to disclosed embodiments.
[0005] The prior art gas mixture supply apparatus, however, has the
following problems.
[0006] According the aforementioned patent, when fuel is supplied
from the upstream fuel injection valve, combustion is improved by
allowing fuel to be deposited on the heater and to be evaporated
therefrom. Accordingly, injection on the side of the main fuel
injection valve is almost completely stopped during the use.
Further, detection of heater current makes it possible to detect
clearly a detectable phenomenon such as a heater current error, for
example, when the heater has been extremely deteriorated or a cable
of the power supply system for the heater has been disconnected.
Even if there is an error as a gas mixture, however, an error of
gas mixture cannot be detected when a not very conspicuous
deterioration of heater performance has occurred or when an error
of the upstream fuel injection valve has occurred even if there is
no error as a heater performance--for example, when there is a
decrease in the area pf flow path, hence decrease in the amount of
fuel injection, for example, due to blocking of a passage for
supplying fuel to the upstream fuel injection valve and mixture of
foreign substances into the fuel injection valve or their
deposition therein. Thus, supply of a sufficient amount of
evaporation fuel is stopped without an error being identified as
such, so the effect of combustion improvement cannot be ensured.
This may lead to increase in the amount of emitted hydrocarbon,
stalling of an engine or complete combustion failure in the worst
case, according to the prior art.
[0007] In the operation mode where independent injection of a gas
mixture supply apparatus with upstream fuel injection valve is
performed after startup by the main fuel injection valve especially
during the period of operation period including startup cranking,
stalling of the engine occurs almost at the same time as it has
started to rotate under its own power if there is an error in the
gas mixture supply apparatus, for example, in the aforementioned
heater or upstream fuel injection valve. Traveling cannot be
performed in the worst case. Such a problem is found out in the
prior art.
[0008] The art disclosed in Japanese Application Patent Laid-Open
Publication Nos. 2000-213398 and 2000-274296 are intended to
improve combustion in the area of high speed and high load
especially though homogenous air intake in a direct injection spark
ignition type internal combustion engine. So switch control means
for sharing control with the main fuel injection valve by operating
the auxiliary fuel injection valve is set in the area of high speed
and high load, and setting is made in advance to ensure that the
air-fuel ratio in concurrent use of the auxiliary fuel injection
valve and main fuel injection valve denotes a rich mixture, while
the air-fuel ratio when fuel is injected only from the main fuel
injection valve shows a lean mixture. Accordingly, if air-fuel
ratio in the case of the main fuel injection valve alone is set to
a weakly lean level, there is no conspicuous change in combustion.
So there is no deterioration in maneuverability which may be felt
as a shock by an operator, and detection is possible in terms of
changes of air-fuel ratio. From the viewpoint of the gas mixture
supply apparatus alone, however, when an error has occurred to the
gas mixture supply apparatus, deterioration in maneuverability is
easily recognized. This requires deterioration of the state of
combustion to be quickly detected. In the detection by an air-fuel
ratio sensor, mainly the O2 concentration is detected, so output on
the side of lean mixture may be produced even in the case of
characteristic misfiring of the engine. Even if mixture is
inadequate as a gas mixture, air-fuel ratio error is not detected
when the ratio between air and fuel is not incorrect. Such a
problem is found in the prior art. Further, the engine starts to
rotate under its own power during the period of operation including
startup cranking. This corresponds to the transient area
characterized by a big change in combustion. Early detection of
deterioration of the state of combustion is difficult, and
diagnosis based on the air-fuel ratio may contain incorrect
detection. Such problem is found out in the prior art.
SUMMARY OF THE INVENTION
[0009] The present invention has been made to solve the
aforementioned problems. The object of the invention is to provide
a diagnostic apparatus for gas mixture supply apparatus and
diagnostic method thereof, capable of,
[0010] finding out an error in gas mixture by the gas mixture
supply apparatus if there is any,
[0011] ensuring at least the engine startup,
[0012] permitting continued operation of the engine without a
problem which may cause stalling of the engine, and
[0013] preventing deterioration of exhaust gas.
[0014] To achieve the above object, a diagnostic apparatus for the
aforementioned gas mixture supply apparatus according to the
present invention is basically characterized in that;
[0015] in a gas mixture supply apparatus of an internal combustion
engine comprising,
[0016] a main fuel injection valve for supplying fuel to an
internal combustion engine,
[0017] an upstream fuel injection valve for supplying fuel to the
area upstream from the aforementioned main fuel injection valve,
and
[0018] gas mixture supply means for supplying gas mixture from
upstream of the aforementioned main fuel injection valve through an
evaporation means for evaporating all or part of fuel supplied from
the aforementioned upstream fuel injection valve;
[0019] the aforementioned diagnostic apparatus for the
aforementioned gas mixture supply apparatus comprises,
[0020] gas mixture state detecting means for detecting the state of
gas mixture when gas mixture is supplied from the aforementioned
gas mixture supply means with the aforementioned evaporation means
operating, and
[0021] evaluation means for evaluating an error of the
aforementioned gas mixture supply means based on the result of
detecting the aforementioned gas mixture state detecting means.
[0022] A diagnostic apparatus for the aforementioned gas mixture
supply apparatus according to the present invention is basically
characterized in that;
[0023] in a gas mixture supply apparatus of an internal combustion
engine for supplying gas mixture from the area upstream of the
aforementioned main fuel injection valve utilizing,
[0024] a main fuel injection valve for supplying fuel to an
internal combustion engine,
[0025] an upstream fuel injection valve for supplying fuel to the
area upstream from the aforementioned main fuel injection
valve,
[0026] a heater member for heating all or part of fuel supplied
from the aforementioned upstream fuel injection valve and
evaporating it, and
[0027] heater control means for controlling application of electric
power to the aforementioned heater member;
[0028] the aforementioned diagnostic apparatus for a gas mixture
supply apparatus comprising,
[0029] gas mixture state detecting means for detecting the state of
gas mixture formed when fuel is supplied from the aforementioned
upstream fuel injection valve with electric power applied to the
aforementioned heater member by the aforementioned heater control
means, and evaluation means for evaluating an error of the
aforementioned upstream fuel injection valve and/or the
aforementioned heater member based on the result of detecting the
aforementioned gas mixture state detecting means.
[0030] The embodiment of a diagnostic apparatus for gas mixture
supply apparatus according to the present invention is configured
in such a way that;
[0031] the aforementioned evaporation means consists of a heater
member and heater control means,
[0032] the aforementioned gas mixture state detecting means detects
gas mixture state based on the result of detecting one or more of
the engine speed, intake manifold pressure, combustion pressure,
torque value, exhaust temperature, HC concentration, NOx
concentration and CO concentration, and
[0033] evaluation means for evaluating the aforementioned error
detests the state of gas mixture based on the result of detecting
at least one of the aforementioned gas mixture state detecting
means, the amount and rate of change, deviation from a
predetermined target value and fluctuating surge.
[0034] A diagnostic apparatus for gas mixture supply apparatus
according to the present invention configured in the aforementioned
manner identifies an error if the state of gas mixture is detected
and a predetermined preset degree of deterioration is exceeded, in
cases where the gas mixture supply apparatus has (1) a
heater-related error caused by <a> decrease in the amount of
evaporated fuel supplied from the upstream fuel injection valve due
to heater deterioration and <b> disconnection of a cable in
power supply system for the heater; or (2) a gas mixture-related
error caused by decrease in the area exposed to flow or decrease in
the amount of fuel injection due to blocking of fuel supply passage
leading to the upstream fuel injection valve or entry or deposition
of foreign substances in the fuel injection valve.
[0035] A diagnostic apparatus for gas mixture supply apparatus
according to the present invention further comprises fail-safe
control means which immediately or progressively implements (1) a
step of reducing the amount of fuel or stopping the supply of fuel
in response to the evaluation made by the aforementioned evaluation
means as containing an error, (2) a step of increasing the amount
of fuel supplied from the aforementioned main fuel injection valve
or switching to the aforementioned main fuel injection valve, (3) a
step of stopping the aforementioned evaporation means or stopping
application of electric power to the aforementioned heater member,
and (4) a step of correcting ignition timing;
[0036] wherein the aforementioned fail-safe control means is used
in such a way as to prevent the operation status of the
aforementioned internal combustion engine and/or the amount of
exhaust gas from being deteriorated.
[0037] A diagnostic apparatus for gas mixture supply apparatus
according to the present invention configured in the aforementioned
manner at least ensures engine startup, permits continued operation
of the engine and prevents deterioration of exhaust gas.
[0038] A diagnostic apparatus for gas mixture supply apparatus
according to the present invention further comprises;
[0039] main fuel supply evaluation means containing (a) a step of
injecting fuel through the aforementioned main fuel injection valve
at least during start cranking, and (b) a step of evaluating fuel
supply as being normal through the aforementioned main injection
valve when engine speed has exceeded a predetermined level or
intake manifold pressure has been reduced below a predetermined
level; and
[0040] a fuel supply change means containing (a) a step of reducing
the amount of fuel or stopping the supply of fuel in response to
the evaluation made by the aforementioned main fuel supply
evaluation means as being normal, (b) a step of increasing the
amount of fuel supplied from the aforementioned upstream fuel
injection valve or switching to the aforementioned upstream fuel
injection valve, and (c) a step of performing operation of the
aforementioned evaporation means or applying electric power to the
aforementioned heater member.
[0041] A diagnostic apparatus for gas mixture supply apparatus
according to the present invention configured in the aforementioned
manner is characterized in that, at least when the aforementioned
main fuel supply means evaluation by a main fuel injection valve
has been found out to be normal, diagnosis is performed by the
upstream fuel injection valve selected by switching. This
characteristic avoids incorrect evaluation which may be caused by
evaluation of an error in gas mixture supply means being adversely
affected by the error of the aforementioned main fuel supply
means.
[0042] A diagnostic apparatus for gas mixture supply apparatus
according to the present invention further comprises;
[0043] an auxiliary air passage for bypassing a throttle valve,
[0044] an auxiliary air passage valve for regulating the amount of
air in the aforementioned auxiliary air passage,
[0045] target speed control means for controlling the
aforementioned auxiliary air passage valve to reach a predetermined
target speed after the aforementioned internal combustion engine
has started and has been evaluated,
[0046] ignition timing control means for controlling ignition
timing to be on the side of delay angle at least when fuel is
supplied from the aforementioned upstream fuel injection valve,
and
[0047] evaluation means for evaluating one or more errors in the
aforementioned upstream fuel injection valve, heater member and
auxiliary air passage valve, based on the result of detection by
the aforementioned gas mixture state detecting means when the
aforementioned ignition timing is controlled to be on the side of
delay angle.
[0048] A diagnostic apparatus for gas mixture supply apparatus
according to the present invention configured in the aforementioned
manner is characterized in that the degree of deterioration can be
evaluated while the state of combustion of ignition timing with
respect to delay angle is detected. This avoids extreme increased
in the amount of hydrocarbon emission or the worse stalling of an
engine.
[0049] Another embodiment of the present invention is characterized
in that the aforementioned ignition timing control means performs
control of ignition timing in terms of delay angle in a
predetermined number of times.
[0050] Still another embodiment of the present invention is
characterized in that the aforementioned gas mixture state
detecting means detects the state of gas mixture based on the
result of detecting one or more of the amounts of air, auxiliary
air passage valve control and fuel injection.
[0051] A further embodiment of the present invention is
characterized comprising;
[0052] means for evaluating the deterioration of battery, and
[0053] means for evaluating the aforementioned gas mixture supply
means for an error based on the result of detecting battery voltage
when fuel is supplied from the aforementioned upstream fuel valve
after evaluation is made to determine that a battery is not
deteriorated.
[0054] Still further embodiment of the present invention is
characterized in that the aforementioned gas mixture state
detecting means detects the state of gas mixture based on;
[0055] the result of detection by heater current detecting means
for detecting the current applied to the aforementioned heater
member, and the aforementioned heater current detecting means
subsequent to electric power to the aforementioned heater member
having been applied to the aforementioned heater member; and
[0056] the trouble setup value of a heater current to be set in
conformity to the amount of fuel injection in advance.
[0057] Still further embodiment of the present invention is
characterized by comprising error storage means for storing an
error when such an error has been found out by the aforementioned
evaluation means, and/or error alarm means for alarming an
error.
[0058] Still further embodiment of the present invention is
characterized in that the aforementioned evaporation means performs
at least one of evaporation by an electric heater, heater
evaporation by combustion, evaporation by ultrasonic vibration,
evaporation by hot water and evaporation by exhaust gas
temperature.
[0059] A diagnostic method for gas mixture supply apparatus
according to the present invention is characterized by
comprising;
[0060] a main fuel injection valve for supplying fuel to an
internal combustion engine,
[0061] an upstream fuel injection valve for supplying fuel to the
area upstream from the aforementioned main fuel injection valve,
and
[0062] gas mixture supply means for supplying gas mixture from
upstream of the aforementioned main fuel injection valve through an
evaporation means for evaporating all or part of fuel supplied from
the aforementioned upstream fuel injection valve; the
aforementioned diagnostic method further comprising;
[0063] a step of detecting the state of gas mixture when gas
mixture is supplied from the aforementioned gas mixture supply
means with the aforementioned evaporation means operating, and
[0064] a step of evaluating an error of the aforementioned gas
mixture supply means based on the aforementioned result of
detection.
BRIEF DESCRIPTION OF THE DRAWINGS
[0065] FIG. 1 is a drawing representing the engine system equipped
with a diagnostic apparatus for a gas mixture supply apparatus as
one embodiment of the present invention;
[0066] FIG. 2 is a drawing representing the configuration inside a
control unit and gas mixture supply apparatus of a diagnostic
apparatus for gas mixture supply apparatus according to the present
embodiment;
[0067] FIG. 3 is a drawing representing a specific method for a gas
mixture supply apparatus of a diagnostic apparatus for gas mixture
supply apparatus according to the present embodiment;
[0068] FIG. 4 is a drawing representing a specific method for a gas
mixture supply apparatus of a diagnostic apparatus for gas mixture
supply apparatus according to the present embodiment;
[0069] FIG. 5 is a drawing representing a specific method for a gas
mixture supply apparatus of a diagnostic apparatus for gas mixture
supply apparatus according to the present embodiment;
[0070] FIG. 6 is a drawing representing further details of a
specific method for a gas mixture supply apparatus of a diagnostic
apparatus for gas mixture supply apparatus according to the present
embodiment;
[0071] FIG. 7 is a drawing representing the relationship between a
change in engine speed .DELTA.N and degree of deterioration in a
diagnostic apparatus for gas mixture supply apparatus according to
the present embodiment;
[0072] FIG. 8 is a drawing representing further details of a
specific method for a gas mixture supply apparatus of a diagnostic
apparatus for gas mixture supply apparatus according to the present
embodiment;
[0073] FIG. 9 is a drawing representing further details of a
specific method for a gas mixture supply apparatus of a diagnostic
apparatus for gas mixture supply apparatus according to the present
embodiment;
[0074] FIG. 10 is a drawing representing the relationship between a
change in parameters and degree of deterioration in a diagnostic
apparatus for gas mixture supply apparatus according to the present
embodiment;
[0075] FIG. 11 is a drawing representing further details of a
specific method for a gas mixture supply apparatus of a diagnostic
apparatus for gas mixture supply apparatus according to the present
embodiment;
[0076] FIG. 12 is a drawing representing the maximum range of
changes .DELTA.Nid and error evaluation value dNB in a diagnostic
apparatus for gas mixture supply apparatus according to the present
embodiment;
[0077] FIG. 13 is a drawing representing the delay angle,
.DELTA.Nid and degree of deterioration in a diagnostic apparatus
for gas mixture supply apparatus according to the present
embodiment;
[0078] FIG. 14 is a drawing representing a method for evaluating an
error in terms of air flow volume Qa in a diagnostic apparatus for
gas mixture supply apparatus according to the present
embodiment;
[0079] FIG. 15 is a drawing representing a method for evaluating an
error of a gas mixture supply apparatus in the normal operating
state in terms of air flow volume Qa in a diagnostic apparatus for
gas mixture supply apparatus according to the present
embodiment;
[0080] FIG. 16 is a drawing representing a method for evaluating an
error of a gas mixture supply apparatus in the normal operating
state in terms of air flow volume Qa in a diagnostic apparatus for
gas mixture supply apparatus according to the present
embodiment;
[0081] FIG. 17 is a drawing representing a method for evaluating an
error of a gas mixture supply apparatus in the normal operating
state in terms of a change of battery voltage in a diagnostic
apparatus for gas mixture supply apparatus according to the present
embodiment;
[0082] FIG. 18 is a drawing representing the relationship between a
change in battery voltage and degree of deterioration in a
diagnostic apparatus for gas mixture supply apparatus according to
the present embodiment;
[0083] FIG. 19 is a drawing representing the relationship between
heater current and heat-on time in a diagnostic apparatus for gas
mixture supply apparatus according to the present embodiment;
[0084] FIG. 20 is a drawing representing fail-safe method when
deterioration has been determined in a diagnostic apparatus for gas
mixture supply apparatus according to the present embodiment;
and
[0085] FIG. 21 is a flow chart representing an error evaluation
step of a gas mixture supply apparatus in a diagnostic apparatus
for gas mixture supply apparatus according to the present
embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0086] The following describes a diagnostic apparatus for gas
mixture supply apparatus and diagnostic method thereof as one
embodiment according to the present invention with reference to
drawings:
[0087] FIG. 1 is a drawing representing the configuration of an
engine system equipped with a diagnostic apparatus for a gas
mixture supply apparatus as an embodiment of the present
invention.
[0088] In FIG. 1, numeral 100 denotes an engine. A sucked air
volume sensor 7 and a throttle valve 8 are mounted in an intake
passage 6 of the engine 100. A main fuel injection valve 2 is
mounted at the intake port inlet of each cylinder. An upstream fuel
injection valve 3 as an air-assisted high atomizing injection valve
and an air passage 11 for capturing fuel atomizing air from
upstream of a throttle valve 8 and supplying it to the upstream
fuel injection valve 3 are provided on the upstream portion of
intake passage 6. It is widely known that fuel generally flows into
the cylinder without depositing on the intake passage if injection
fuel is atomized to about ten microns in diameter. Injection fuel
of the upstream fuel injection valve 3 is atomized to about ten
microns to ensure that the fuel attached to the intake passage 6
will be reduced.
[0089] A heater member 4 (evaporation means) is installed on the
upstream fuel injection valve 3 in the direction of injection. A
PTC heater (thermister with positive characteristic) capable of
keeping temperature at a predetermined level can be used as heater
member 4. The PTC heater is a self-heat generation and self-control
type heater which automatically increases the Joule heat of OTC
heater itself and keeps heater temperature constant, despite
reduction of ambient temperature. The operation temperature is
uniquely defined by its material composition, and can be selected
in the temperature range from 100 to 300 degrees Celsius. Further,
the Curie point can be freely changed by changing the composition
of the PTC ceramic constituting the PTC heater. Electric power is
supplied to this heater member 4 from a battery 12 via a heater
relay 13. Heater current is detected by the terminal voltage of
heater current detecting means 20 (heater current detecting
means).
[0090] An auxiliary air passage 9 bypassing a throttle valve 8 is
provided with an idle speed control valve (hereinafter referred to
as "ISC valve") for adjusting the amount of auxiliary air, or an
auxiliary air passage control valve 10 such as air valve for
opening or closing the passage by turning on or off electric
power.
[0091] Here the auxiliary air passage 9 has its outlet formed in
such a way that air will be directed toward the heater member 4.
There is a slight variation in the fuel particle diameter of
upstream fuel injection valve 3. Some fuel particles have greater
diameter. The fuel injected from the upstream fuel injection valve
3 and having smaller particle diameter is carried to the downstream
area by air flow and is put directly into the cylinder. This allows
only the fuel with greater particle diameters to be deposited on
the heater member 4 and to be evaporated.
[0092] A gas mixture supply apparatus 21 is composed of the
aforementioned upstream fuel injection 3, auxiliary air passage 9,
passage valve 10, air passage 11, heater member 4 and heater
current detecting resistor 30.
[0093] Air whose flow rate is adjusted by a throttle valve 8 and
which is promoted for evaporation by the heater member 4 is mixed
with fuel injected from the fuel injection valve (injector) 3
arranged on the upstream side of the cylinder and is supplied to
each cylinder, and is subjected to combustion.
[0094] Exhaust gas of fuel burnt in each of the aforementioned
cylinders is led to a catalyst converter (not illustrated) through
an exhaust pipe 31 where it is purified and discharged. An oxygen
concentration sensor 33 for sending an air-fuel ratio signal linear
with respect to exhaust air-fuel ratio is arranged on an exhaust
pipe 31 wherever required.
[0095] An intake manifold pressure sensor 30 for detecting pressure
in the intake manifold on the downstream side of the heater member
4 intake passage 6,
[0096] a crank angle sensor 14 set to a predetermined crank angle
position of the engine as one of the means for detecting the engine
speed,
[0097] an ignition apparatus for supplying ignition energy to an
ignition plug 16 for firing the gas mixture of fuel supplied into
the engine cylinder through an ignition coil 17 and a power switch
18 based on ignition signal,
[0098] a hot water sensor 15 for detecting engine coolant
temperature and
[0099] a combustion pressure sensor 33 for detecting combustion
pressure in the cylinder are arranged at respective specified
positions of the aforementioned engine 100.
[0100] Each sensor signal is sent to a control unit 19, and the
main fuel injection valve 2, upstream fuel injection valve 3,
heater member 4, heater relay 13, ISC valve 10 and power switch 18
are controlled by the control unit 19.
[0101] The aforementioned oxygen concentration sensor 32 shown in
the present embodiment outputs a signal proportional air-fuel ratio
of exhaust gas. It may output two signals for exhaust gases on the
rich and lean sides with respect to theoretical air-fuel ratio.
[0102] The control unit 19 is arranged in the car body or engine
room. Based on the electrical signal sent from the aforementioned
various sensors, this unit performs predetermined computations. To
ensure the optimum control of the operation, it produces signals
for opening/closing operation of the upstream fuel injection valve
3 and main fuel injection valve 2, driving of heater member 4,
actuation of ignition plug 16, and opening/closing operation of the
aforementioned idling speed control valve. Further, the control
unit 19 provides air-fuel ratio control of the mixture gas supplied
to the aforementioned engine, ignition control and idling speed
control (ISC) as well as fuel control including an air-fuel ratio
correction coefficient learning method.
[0103] FIG. 2 is a drawing representing the configuration inside a
control unit 19 and gas mixture supply apparatus 21. The control
unit 19 comprises;
[0104] an input/output interface (I/O) for converting electric
signals of sensors installed on the engine into signals for digital
computation, and signals for digital computation into actuator
drive signals,
[0105] a computation apparatus (MPU) for identifying engine state
from the signal for digital computation sent from the I/OLSI,
calculating the volume of fuel required by the engine and ignition
time according to the programmed procedure and sending the result
of calculation to the I/OLSI,
[0106] a non-volatile memory (EP-ROM) for storing the computation
apparatus control procedure and control constant, and
[0107] a volatile memory (RAM) for storing the result of
calculating the computation apparatus.
[0108] The aforementioned I/O LSI into digital computation signals
the digital signals of the aforementioned sucked air volume sensor
7, the aforementioned crank angle sensor 14, the aforementioned
coolant temperature sensor 15, the aforementioned intake manifold
pressure sensor 30, the aforementioned oxygen concentration sensor
33, and various sensors for a ignition switch, battery voltage,
clutch switch, etc.
[0109] The aforementioned computation apparatus (MPU) identifies
the state of the engine 100 based on the digital computation signal
converted by the aforementioned I/OLSI, calculates the fuel volume
required by this engine 100 and ignition timing according to the
procedure predetermined by the aforementioned EP-ROM, stores the
result of this calculation in the aforementioned RAM and sends it
to the aforementioned I/OLSI. This I/OLSI converts the digital
control signal into the drive signal of each actuator, and sends
each of the drive signals for opening command value, first to n-th
cylinder fuel injection valve signal and first to n-th cylinder
ignition coil signal to the idling speed control valve, upstream
fuel injection valve 3, main fuel injection valve and ignition flag
16. The aforementioned RAM is connected with the backup power
supply to store the memory contents even when power is not supplied
to the control unit 19.
[0110] The gas mixture supply functional section of the
aforementioned control unit 19 comprises;
[0111] gas mixture supply apparatus error evaluation means 3,
[0112] a gas mixture supply apparatus fail-safe means 23,
[0113] injection control means 1 for controlling an upstream fuel
injection valve 3 and main fuel injection valve 2,
[0114] heater control means 5,
[0115] passage valve control means 40 for controlling passage valve
10, and
[0116] ignition timing control means 41 for controlling an ignition
coil 17.
[0117] In FIG. 2, the gas mixture supply apparatus 21 comprises
heater current detecting means 20 consisting of an upstream fuel
injection 3, passage valve 10, heater relay 13 and heater member 4
and heater current detecting resistor.
[0118] The following describes the operation of the diagnostic
apparatus for gas mixture supply apparatus 21 and diagnostic method
thereof as configured in the manner described above.
[0119] First, The following shows the specific method of
functioning of gas mixture supply apparatus error evaluation means
23 for detecting an error of gas mixture supply apparatus 21, with
reference to FIGS. 7 to 5.
[0120] FIG. 1 is a drawing representing a specific method of gas
mixture supply apparatus error evaluation means 23.
[0121] FIGS. 3 to 5 show an example of the gas mixture supply
apparatus 21 comprising a heater member as evaporation means for
heating and evaporating all or part of the injection fuel of the
upstream fuel injection valve 3 in the direction of injection from
a passage valve 10, a upstream fuel injection valve and the
aforementioned upstream fuel injection valve 3.
[0122] In the aforementioned configuration, especially the gas
mixture by evaporation means provides an advantage of reducing the
amount of the emission of hazardous hydrocarbon (HC) after startup
of a freezer, by increasing the delay angle of ignition timing,
raising the exhaust gas temperature and promoting the activity of
catalyst, without depending on such gasoline properties as mass and
light weight. Accordingly, the state of gas mixture appears most
conspicuously in the engine behavior. Thus, to ensure quick
detection of the state of gas mixture, the most preferred method is
to get correct information on engine behavior. Another method is to
check the state of engine combustion by gas mixture and components
of exhaust gas to evaluate the state of gas mixture.
[0123] FIG. 3 is a drawing representing the behavior of engine
speed when gas mixture is supplied from the gas mixture supply
apparatus after engine startup.
[0124] In FIG. 3, a solid line shows the behavior where there is no
error to the gas mixture supply means, while a broken line shows
the case where there is some problem. In this case, the change of
engine speed N is greater than when there is no error.
[0125] When the aforementioned gas mixture state detecting means
detects the engine speed, evaluation means for evaluating an error
of the aforementioned gas mixture supply means is based on the
method of detecting in terms of the range .DELTA.N of the maximum
change in the engine speed during the specified period (tmm) shown
in FIG. 3, the method of detecting in terms of the maximum value
.DELTA.dNm in a predetermined time (tmm) by detecting the change
(dN) in a predetermined time (dt) or the method of evaluating in
terms of the deviation (dNmea) from the target engine speed (Nmea)
as shown in FIG. 4. Without being restricted to these methods,
combustion of only a particular cylinder can be deteriorated due to
the difference in the change among various cylinders. Accordingly,
it is possible to make evaluation in conformity to the magnitude of
surge occurring within a predetermined time (tmm).
[0126] FIG. 5 is a drawing representing the behavior of the engine
speed when operation is started by the upstream fuel injection
valve 3 subsequent to startup cranking and application of electric
power. The gas mixture supply apparatus 21 is evaluated as
containing an error if the engine speed has failed to reach a
predetermined value, in a predetermined time from cranking, e.g.
within 5 to 10 seconds after cranking has started when the ambient
temperature is normal 30 degrees Celsius, and within 30 seconds at
an extremely low temperature.
[0127] FIG. 6 is a drawing representing the details of a specific
operation method of gas mixture supply apparatus error evaluation
means 23.
[0128] First, startup cranking is carried out by a starter and
injection is performed by main fuel injection valve 2 to start up,
as shown in FIG. 6(c). This is because, when gas mixture is
supplied only by gas mixture supply apparatus 21 from the start,
mixture is supplied from the upstream side if the main fuel
injection valve 2, so there is a big intake manifold volume up to
the cylinder resulting in a delay of transport, and this requires a
long startup time. So solve this problem, fuel is supplied by the
main fuel injection valve 2 at the time of startup. After the
engine has started, gas mixture is supplied from the gas mixture
supply apparatus 21 by a switching method. This has an advantage of
reducing the startup time. Further, when evaluation of the
aforementioned main fuel supply means using the main fuel injection
valve 2 is correct without error, diagnosis is performed by
switching to the upstream fuel injection valve 3. This prevents
incorrect evaluation from being made by error evaluation for gas
mixture supply means being adversely affected by some error of the
aforementioned main fuel supply means.
[0129] Fuel is supplied by the upstream fuel injection valve 3 from
the time of cranking. Fuel supply means of main fuel injection
valve 2 is evaluated as normal by main fuel supply evaluation means
if the engine speed has reached a predetermined value (complete
explosion evaluation level), e.g. 800 rpm within a predetermined
time, e.g. within 10 seconds after cranking has started when
ambient temperature is normal 30 degrees Celsius or more, or within
30 seconds at an extremely low temperature. If the engine speed
fails to reach the predetermined time, the main fuel injection
valve 2 and other devices or the like related to main fuel
injection are evaluated as containing an error. After the main fuel
injection valve 2 has been evaluated as normal, the share of
injection of the main fuel injection valve 2 is subjected to a
stepwise reduction, and this injection is stopped ultimately, as
shown by a solid line in FIG. 6(c). In the meantime, if the
injection by upstream fuel injection valve 3 is reduced in a
stepwise manner as shown by a solid line in FIG. 6(d), then there
is less delay on the fuel inflow into the cylinder than when
startup is performed by the upstream fuel injection valve 3. Less
fuel is deposited on the intake passage evaporated fuel is supplied
by upstream fuel injection valve 3 after startup, without startup
property being deteriorated. So the stability is improved, and
hence combustion is improved. Further, in this case, application of
electric power to heater member 4 is started upon starting of the
injection by upstream fuel injection valve 3, as shown in FIG.
6(b).
[0130] After the aforementioned upstream fuel injection valve 3 has
started injection, delay angle of ignition timing can be corrected,
and exhaust temperature can be raised to promote the activity of
catalyst, as shown in Fig. (e). With consideration given to power
consumption by the heater member 4, for example, electric power is
applied to the heater member 4 for tens of seconds before
activation of catalyst after freezer startup, and injection is
carried out by the and upstream fuel injection valve 3 to promote
activation of catalyst. Before traveling is started after that (not
illustrated), injection of upstream fuel injection valve 3 and
application of electric power to the injection and heater member 4
are stopped. Then injection is performed after switching to the
main fuel injection valve 2.
[0131] Means for switching between the aforementioned main fuel
injection valve 2 and upstream fuel injection valve 3 controls the
amount of fuel in a stepwise manner in such a way that the fuel is
supplied independently. If control of the amount of is given in
terms of injection pulse width, it is also possible to set up an
ineffective pulse width wherein a required volume of fuel cannot be
supplied even if pulse width is given. Further, switching mean is
also provided if the share of injection on the part of the
injection valve as a major fuel supplier is set to a greater
percentage.
[0132] In the engine speed shown in Fig. (a), the behavior
indicated by a solid line shows the case where there is no problem
to the performance of the gas mixture supply apparatus 21
consisting of the upstream fuel injection valve 3. Detection is
made of the maximum variation range .DELTA.N1 of engine speed
within a predetermined time set in terms of tmm after a
predetermined tmd after the delay angle of ignition timing shown in
FIG. 6(e) is corrected up to a predetermined volume subsequent to
startup of injection of the upstream fuel injection valve 3.
[0133] In the meantime, a broken line in FIG. 6(a) shows the
behavior suggestive of some problem with the gas mixture supply
apparatus 21 consisting of upstream fuel injection valve 3, for
example, decrease in evaporated fuel supplied from the upstream
fuel injection valve 3 due to heater deterioration, heater-related
error due to cable disconnection in the power supply system to the
heater member 4, or reduction in the area of the flow path due to
blocking of the fuel supply passage to the upstream fuel injection
valve 3 and entry or deposition of foreign substances in the fuel
injection valve, resulting in decrease in the volume of fuel
injection. The amount of change in speed is greater than when there
is no problem. Detection is made of the maximum range .DELTA.N3 of
change in engine speed within a predetermined time set in terms of
tmm in a predetermined tmd from the time when the delay angle of
the ignition timing shown in FIG. 6(e) is corrected to a
predetermined volume (drtd). Accordingly, an error of the gas
mixture supply apparatus 21 can be evaluated in terms of the
maximum range of change in engine speed. Assume that the maximum
range of change during this tmm is .DELTA.N, then
.DELTA.N1<.DELTA.N3. The magnitude of .DELTA.N is correlated
with the state of an error in the gas mixture supply apparatus 21,
for example, the percentage of heater deterioration.
[0134] FIG. 7 is a drawing representing the relationship between
the amount of change in engine speed .DELTA.N and degree of
deterioration. As the degree of deterioration is greater, an error
is more likely to be evaluated, as shown in FIG. 7. In this case,
the aforementioned amount of change in engine speed .DELTA.N is
approximately proportional to the degree of deterioration. The
degree of deterioration is given in terms of a predetermined
function of .DELTA.N. Thus, a value affecting the exhaust gas
performance and engine operation is preset as an evaluation value
SLne. If .DELTA.N exceeding this value has been detected, an error
is determined. Alternatively, if .DELTA.N exceeding this value has
been found out, an error is determined. Alternatively, the degree
of deterioration is obtained in a stepwise manner in conformity to
.DELTA.N. When a predetermined degree of deterioration has been
exceeded, an error is determined.
[0135] FIGS. 8 and 9 are drawing representing further details of a
specific method used in gas mixture supply apparatus error
evaluation means 23.
[0136] Similarly to FIG. 6, FIG. 8 shows the aforementioned gas
mixture state detecting means other than engine speed during a
predetermined time period set in terms of tmm in a predetermined
tmd from the time when delay angle of ignition timing shown in FIG.
8(e) has been corrected up to a predetermined amount after start of
injection by the upstream fuel injection valve 3. It also shows a
method of detecting an error of the aforementioned gas mixture
supply apparatus 21 based on intake manifold pressure FIG. 8(f),
combustion pressure in FIG. 8(g), torque value in FIG. 8(h) and HC
concentration in FIG. 8(i).
[0137] Intake manifold pressure is detected by an intake manifold
pressure sensor 30 installed on the intake manifold, combustion
pressure by combustion pressure sensor 33 located in the vicinity
of combustion chamber, torque value by a torque sensor mounted on
the engine output shaft, and the HC concentration by HC sensor
mounted on the exhaust pipe of engine 100. Similarly to FIG. 6,
each solid line indicates the behavior when the aforementioned gas
mixture supply apparatus 21 has no performance problem. The broken
line indicates the behavior when the aforementioned gas mixture
supply apparatus 21 has some problem. If there is no problem, gas
mixture state detecting means shown in FIGS. 8(f) to (i) during the
time period set in terms of tmm in a predetermined tmd from the
time when the delay angle of ignition timing has been corrected up
to a predetermined amount shown in FIG. 8(e) exhibits very small
change, similarly to FIG. 6. However, if there is any problem, the
change is greater than when there is no problem. This makes it
possible to evaluate an error of the aforementioned gas mixture
supply apparatus 21 in terms of the amount of change.
[0138] FIG. 10 shows the relationship between the amount of change
in each parameter and degree of deterioration. FIGS. 10(f) to (i)
correspond to the previous Figs. (f) to (i) and FIGS. 10(j) and (k)
to Figs. (j) and (k) to be explained later.
[0139] When detection is made in terms of the amount of change
.DELTA.Pm of the intake manifold pressure in FIG. 8(f), the
magnitude of .DELTA.Pm is correlated to the state of an error in
gas mixture supply apparatus 21, for example, to the degree of
deterioration of the heater.
[0140] FIG. 10(f) shows the relationship between the aforementioned
.DELTA.Pm and the degree of deterioration. In this case, the
aforementioned dPm and degree of deterioration are almost
proportional to each other. The degree of deterioration is given by
a predetermined function of .DELTA.Pm. Accordingly, when .DELTA.Pm
exceeding a preset threshold value SLPm has been detected, an error
is determined. Alternatively, it is also possible to obtain the
degree of deterioration in a stepwise manner in response to
.DELTA.Pm. When the preset degree of deterioration has been
exceeded, an error is determined.
[0141] Similarly, when detection is made in terms of the amount of
change in combustion pressure .DELTA.Pi in FIG. 8(g) or the amount
of change in torque value .DELTA.Tq in FIG. 8(h), the magnitude of
.DELTA.Pi and .DELTA.Tq is correlated with the state of error in
gas mixture supply apparatus 21, for example, the degree of
deterioration of the heater.
[0142] FIGS. 10(g) and (h) shows the relationship between the
magnitude of the aforementioned .DELTA.Pi and .DELTA.Tq and the
degree of deterioration. The degree of deterioration is given in
terms of a predetermined function. Accordingly, when .DELTA.Pi and
.DELTA.Tq exceeding the preset threshold value SLPi and SLTq have
been detected, an error is determined.
[0143] Further, the HC concentration sensor in FIG. 8(i) is
installed on the exhaust pipe to detect the exhaust gas component.
As discussed above, the air-fuel ratio sensor 33 may produce the
output on the side of lean mixture even in the case of
characteristic misfiring of the engine. Even if mixture is
inadequate as a gas mixture, air-fuel ratio error is not detected
when the ratio between air and fuel is not incorrect. Such a
problem is found in the prior art. Further, the engine starts to
rotate under its own power during the period of operation including
startup cranking. This corresponds to the transient area
characterized by a big change in combustion. Early detection of
deterioration of the state of combustion is difficult, and
diagnosis based on the air-fuel ratio may contain incorrect
detection. Such problem is found out in the prior art. When HC
concentration method is used, combustion is affected by gas mixture
by detection of exhaust gas component, with the result that the
state of combustion is changed. This allows quicker detection of a
change in exhaust gas component than the air-fuel ratio sensor 32,
thereby ensuring reliable evaluation of a problem in gas mixture.
FIG. 10(i) shows the relationship between the degree of
deterioration and evaluation value (SLHC) when the change in HC
concentration is used for detection.
[0144] The sensor for detecting the exhaust gas component includes
a NOx sensor (not illustrated). A problem of gas mixture can be
evaluated by the change in concentration detected in the same
manner. Further, when an exhaust gas temperature sensor (not
illustrated) is mounted on the exhaust pipe, combustion is affected
by gas mixture with the result that the state of combustion is
subjected to change. Thus, change in exhaust gas temperature is
detected and a problem in gas mixture can be evaluated.
[0145] FIG. 9 shows the case of FIG. 8 with an additional
installation of (1) an auxiliary air passage 9 for bypassing the
throttle valve 8, (2) an auxiliary air passage valve 10 for
regulating the amount of air in the aforementioned auxiliary air
passage 9, and (3) target speed control means for controlling the
aforementioned auxiliary air passage valve 10 so that a
predetermined target speed can be achieved, after the
aforementioned internal combustion engine is determined to have
started. Similarly to FIG. 9, each solid line indicates the
behavior when the aforementioned gas mixture supply apparatus 21
has no performance problem, whereas each broken line indicates the
behavior when there is some problem with the aforementioned gas
mixture supply apparatus 21. If delay angle of ignition timing is
corrected up to a predetermined level in the state of target speed
control, there will be an increase in the amount of air to produce
the required torque in order to maintain the speed, with the result
that the amount of fuel is increased. In the present configuration,
evaluation is made to determine that any one or more of the
aforementioned upstream fuel injection valve 3, heater member 4,
and auxiliary air passage valve 10 have a problem.
[0146] When the amount of air is as shown in FIG. 9(j), the engine
speed is reduced below the target value, if there is any problem
with the aforementioned gas mixture supply apparatus 21. So control
is made in such a way as to increase the amount of air in the
bypass such as auxiliary air passage valve (ISC valve) 10 to
maintain the target speed, with the result that the amount of air
is increased. Thus, means is provided to detect the change in the
amount of air (Qa) within the time period preset in terms of tmm in
a predetermined time tmd from the time when the delay angle of
ignition timing is corrected upstream to a predetermined level as
shown in 9(e). For example, an error of gas mixture supply
apparatus 21 can be found out according to the magnitude of the
maximum range of change (.DELTA.Qa). Assume that the maximum range
of change on this tmm is .DELTA.Qa. There is a relation of
.DELTA.Qa<.DELTA.Qa2 between the .DELTA.Qa1 detected when there
is no performance problem and .DELTA.Qa2 detected when there is
some performance problem. Thus, the magnitude of .DELTA.Qa is
correlated with n error of the gas mixture supply apparatus 21, for
example, with the degree of deterioration of the heater. FIG. 10(j)
shows the relationship between the aforementioned .DELTA.Qa and the
degree of deterioration. In this case, it is given in terms of a
function of the aforementioned .DELTA.Qa. Thus, when .DELTA.Qa
exceeding this value has been detected, it is determined as an
error. Alternatively, it is also possible to obtain the degree of
deterioration in a stepwise manner in conformity to .DELTA.Qa, and
to determine an error when a predetermined degree of deterioration
has been exceeded.
[0147] Further, it is also possible to use the following step: To
detect the change in Qa, the amount of air in the bypass such as
ISCV valve 10 is detected as an increase .DELTA.BA for tmm after
the lapse of the aforementioned tmd wherein the amount of control
prior to execution of correction of the delay angle in the
aforementioned ignition time is used as a reference. An error
evaluation value SLba is preset, and the degree of deterioration is
obtained, accordingly.
[0148] Similarly, FIG. 10(k) shows the degree of deterioration when
detection is made in terms of the change of fuel flowing into the
cylinder .DELTA.qf in FIG. 9(k) and evaluation value (SLqf). It is
also possible to detect qf according to the change in amount of
fuel (g/min.) calculated by the control unit or in the time (ms)
when the upstream fuel injection valve 3 is open.
[0149] When startup is made by the upstream fuel injection valve 3
as shown in the aforementioned FIG. 3, it may not be determined
that the fuel supply means of the gas mixture supply apparatus 21
is normal even when the engine speed has reached a predetermined
value. For example, when the degree of deterioration is small, the
conditions on the aforementioned speed are satisfied. So in the
next step, delay angle of ignition timing is corrected to reach the
predetermined value, shown in the aforementioned FIG. 8(e), and the
aforementioned range of change in engine speed is detected. When
the preset degree of deterioration has been exceeded, an error is
determined. When it has been determined that error evaluation has
been confirmed, correction of the delay angle of ignition timing is
stopped, and the fail-safe means to be described later is operated.
Then control is made in such a way as to be switched to the fuel
supply means by the aforementioned main fuel injection valve 2.
[0150] FIG. 11 is a drawing showing further details of a specific
method of the gas mixture supply apparatus error evaluation means
23. It shows an example of the case shown in FIG. 6.
[0151] In the aforementioned FIG. 6, after injection of the
aforementioned upstream fuel injection valve 3 is started, delay
angle of ignition timing shown i FIG. 6(e) is continued to be
corrected to reach the predetermined level. In FIG. 11, by
contrast, delay angle of ignition timing is carried out in several
steps (n steps). A change in engine speed is detected in the steady
mode during ignition timing to find out an error or the state of
deterioration of the aforementioned gas mixture supply apparatus
21.
[0152] First, after the operation has been switched to the
injection by the upstream fuel injection valve 3, the angle of
ignition timing is delayed gradually to reach a predetermined level
(drt1), and this state is maintained. Then it is possible to
detects the maximum range of change in engine speed .DELTA.Nidl
within the time set on tm1 after the lapse of a predetermined time
(tmd),
[0153] FIG. 12 shows the maximum range of change .DELTA.Nid and
error evaluation value dNB. FIG. 12 indicates the aforementioned
maximum range of change .DELTA.Nid and the preset error evaluation
value dN8. The dNB is set to a value with comfortable margin with
respect to the maximum range of change .DELTA.NA with the normal
scope. If Nidl<dNB to be detected within the scope of the
aforementioned tm1, the aforementioned gas mixture supply apparatus
2 is considered to be free of an error, and the angle of ignition
timing is continued to be gradually delayed to reach the preset
value (drt2). The maximum range of change .DELTA.id2 of the engine
speed within the time preset on tm3 after the lapse of a
predetermined time (tdm) is detected.
[0154] If .DELTA.Nid2<dNB, the aforementioned gas mixture supply
apparatus 21 is assumed to have no error, and the angle of ignition
timing to reach a predetermined value (drtn) to be described later.
Then that state is maintained. After the lapse of a predetermined
time (tmd), the maximum range of change .DELTA.dn of the engine
speed within the predetermined time set on the tmn is detected in
the same way. The angle is delayed in several steps (n steps) until
the finally required delay angle drtd is reached. If there is no
change in speed where .DELTA.Nidn.gtoreq.dNB is reached Before the
angle is delayed to reach the d4rdt, the aforementioned gas mixture
supply apparatus 21 is evaluated as normal. If
.DELTA.Nidn.gtoreq.dNB is found during the delay of the angle on
the way, an error is determined. Further, if the total time
.SIGMA.tm before reaching the required amount of delay angle for
ignition timing is not as short as 20 seconds or less in actual
execution, the effect of raising exhaust gas temperature will be
reduced, and deterioration of exhaust gas will result, so it is
necessary to select the proper number of steps (n sets) and the
aforementioned times tmd and tmn. `n` is preferred to be about 2 to
three, and .SIGMA.dtm should be set to 5 to 10 seconds.
[0155] FIG. 13 is a map showing the delay angle .DELTA.Nid and the
degree of deterioration. Only error evaluation is made in FIG. 12.
By contrast, the degree of deterioration is preset in the form of a
map from the relationship between delay angle and .DELTA.Nid with
respect to .DELTA.Nidn in each stage in n-steps ignition timing in
FIG. 11. In response, the state of deterioration of the
aforementioned gas mixture supply apparatus 21 is evaluated in each
stage. For example, setting is made in such a way that the degree
of deterioration is large even when .DELTA.Nid detected when the
delay angle is as small as 5 degrees is 100 r/min., and the degree
of deterioration is small even when .DELTA.Nid detected when the
delay angle is as large as 20 degrees is 100 r/min. Similarly to
the case of the aforementioned FIG. 6, it is also possible obtain
it by detecting a change in engine speed in terms of the magnitude
of the maximum value of the change (.DELTA.Nm) in a predetermined
time, in addition to .DELTA.Nid, or by detecting the magnitude of
the deviation (dNmea) from the target engine speed.
[0156] In the diagnostic apparatus configured in the aforementioned
manner, according to the method where the delay angle of ignition
timing is gradually delayed to a predetermined level as shown in
the aforementioned FIG. 6, when there is a large degree of
deterioration of the upstream fuel injection valve 3 (e.g. severe
deterioration, heater wire disconnection, extremely insufficiency
of fuel supply), combustion will be deteriorated before angle delay
is completed, possibly resulting in increase of the amount of
discharged hydrocarbon or stalling of the engine in the worst case.
By contrast, stepwise angle delay allows the degree of degradation
to be evaluated while detecting the state of combustion with
respect to the amount of delay angle. This eliminates the
possibility of extreme increase in the amount of discharged
hydrocarbon or engine stalling in the worst case.
[0157] FIG. 14 is a drawing representing the method of evaluating
an error in terms of air flow rate Qa.
[0158] As shown in FIG. 14, if the angle of ignition timing is
delayed, control is made in such a way as to increase the amount of
air. Thus, an error is determined if increase in the amount of air
(dQa) in conformity to the delay angle of ignition timing ha
exceeded the evaluation value line (dQaB which is preset as a table
value or function with respect to the amount of ignition angle with
comfortable margin, for the line dQaA obtained at the normal
time.
[0159] According to the same concept as the error evaluation method
described with reference to FIGS. 12 to 14, similarly to the case
of FIG. 8 (not illustrated), an error or degree of deterioration
can be evaluated even when setting an error line in response to the
amount of change in the intake manifold .DELTA.Pm as another gas
mixture state detecting means in response to the delay angle for
ignition timing, or when setting an error evaluation line in
response to the change in the amount of fuel flowing into the
cylinder .DELTA.qf.
[0160] With reference to FIGS. 15 to 17, the following will
describer the method of the evaluating an error or deterioration of
the aforementioned gas mixture supply apparatus 21 under normal
operating condition in addition to the condition immediately after
startup.
[0161] FIGS. 15 and 16 show how to evaluate an error of a mixture
supply apparatus under the normal operating conditions.
[0162] In FIG. 15, a switching device is provided to perform
forcible switching from independent operation by the main fuel
injection valve 2 under the normal condition to the independent
operation by the upstream fuel injection valve 3. This switching
device is installed in the area where maneuverability is less
affected, for example, in the high-sped and high-load area. The
injection valve is switched on the assumption that no error is
determined during the operation independently by the main fuel
injection valve 2. After the injection valve has been switched,
similarly to the case shown in FIG. 6, an error of the gas mixture
supply apparatus 21 is evaluated in terms of the magnitude of the
maximum range of change in the engine speed in conformity to the
maximum range of change .DELTA.N in engine speed within a
predetermined time to be set on tmm after a predetermined tmd2.
After the lapse of time tck subsequent to switching, the
independent operation by the main fuel injection valve 2 is
resumed. However, if there is a change resulting in
.DELTA.N>.DELTA.N3 as shown in FIG. 6, the operation returns to
the independent operation by the main fuel injection valve 2 even
before the lapse of time tck. If a serious error is found out,
sale-safe means is utilized.
[0163] FIG. 17 is a drawing representing how to evaluate an error
of a gas mixture supply apparatus according to the change in
battery voltage. It shows a method for evaluating an error or
deterioration of the aforementioned gas mixture supply apparatus 2
according to the change in battery voltage (VB) when the
independent operation by the main fuel injection valve 2 is
switched over to the independent operation by the upstream fuel
injection valve 3, as shown in FIGS. 6, 8, 15 and 16.
[0164] When the operation mode is switched, the heater changes from
off-state (power off) to on-state (power on). This results in
consumption of heater current and reduction in battery voltage
(VB). The heater current reaches the maximum value when the heater
is turned on. An error or E6392Adeterioration can be evaluated by
detecting the maximum range of change (.DELTA.VB) when the heater
is turned on, or the maximum percentage of the change (dvb). If
there is no deterioration there is a large inrush current when the
heater is turned on, and the range of change in VB tends to
increase.
[0165] FIG. 18 is a drawing representing the change in battery
voltage and degree of deterioration.
[0166] The aforementioned .DELTA.VB and degree of deterioration are
approximately inversely proportional to each other. The degree of
deterioration is given in terms of the function of .DELTA.VB. Thus,
an error is determined when .DELTA.VB not exceeding a predetermined
value SLvb has been detected. It should be noted, however, in this
case that the value .DELTA.VB is detected as a large value when the
battery itself is deteriorated or is not sufficiently charged. So
even if the heater is deteriorated, an error is not determined in
some cases. Thus, when the heater is off, the battery VB is 12
volts or more when the engine is stopped, and is about 14 volts
when an alternator is generating power. In this case, the battery
is evaluated as normal. Based on this assumption, evaluation is
made according to the change in battery voltage (VB). This is an
important point.
[0167] FIG. 19 is a drawing representing the relationship between
heater current and the time when the heater is tuned on. It shows
the configuration in FIG. 2 wherein an error or deterioration of
the aforementioned gas mixture supply apparatus 21 is determined
when a heater current detecting means 20 is provided.
[0168] Assume that the horizontal axis indicates the time elapsed
for switching from the off-state of the heater to the on-state.
When there is no error, the heater current value to be detected
takes a value below a predetermined value, e.g. a value below 200A,
where the maximum value appears immediately after power is turned
on. So in the present embodiment, current evaluation values SLap1,
SLap2 and SLap3 are set in three stages of tdal, tdal2 and tdal3
respectively according to the passage of time. If the predetermined
time has been exceeded in each stage, an error is determined. Here
the evaluation value can be one SLap1 value aiming at the maximum
value, or more than three stages can be used. When obtained from
the change in heater current, two or three stages are preferable.
The current value changes with the amount of fuel attached to the
heater due to the amount of injected fuel. So evaluation accuracy
will be improved and incorrect diagnosis will be prevented if
evaluation values SLap1, SLap2 and SLap3 are set according to the
amount of injected fuel in advance.
[0169] FIG. 20 is a drawing representing a fail-safe method for
deterioration evaluation. It shows a fail-safe method when an error
or deterioration has been evaluated according to the method for
evaluating the aforementioned gas mixture supply apparatus 21. At
least, it shows the method for ensuring engine startup, continued
operation of the engine and prevention of exhaust gas from being
deteriorated.
[0170] As shown in FIG. 20(d), when operation is performed by
upstream fuel injection valve 3 alone or by the fuel supply means
for setting a greater share of fuel supply by gas mixture supply
apparatus 21 alone, and when it has been determined that error
evaluation is confirmed, then delay of ignition timing angle for
promoting activation of the catalyst shown in FIG. 20(e) is
stopped. After the ignition timing is controlled to reduce the
shock due to switching of the fuel supply means, ignition time is
controlled so as to stop delay of angle. Control is made in such a
way as to switch from the aforementioned main fuel injection valve
2 alone shown in 20(c) or the aforementioned gas mixture supply
apparatus 21 to the fuel supply means for setting greater share of
fuel supply for the main fuel injection valve 2. In some cases, the
power supplied to the heater shown in FIG. 20(b) should be turned
off after evaporating the fuel injected by the upstream fuel
injection valve 3. But in other cases, it should be turned off when
the aforementioned heater has been evaluated as containing an
error. So the time from confirmation of error evaluation to turning
off of the heater (dltn2) is set in order to ensure that the time
of turning it off can be selected depending on the result of error
evaluation,
[0171] The embodiment of the diagnostic apparatus described so far
is based on the understanding that the fuel injection valve
provided close to the suction port is the main injection valve 2.
It is also possible to use the injection valve for direct injection
of fuel into the combustion chamber as the main fuel injection
valve. There is no difference in the method of diagnosis and the
advantages derived therefrom.
[0172] The following describes the error evaluation control for the
gas mixture supply apparatus 21 in the aforementioned
embodiment:
[0173] FIG. 21 is a flow chart showing error evaluation for the gas
mixture supply apparatus 21. In the computation apparatus (MPU) of
the control unit 19, startup is executed by the main routine (not
illustrated) at every predetermined time interval.
[0174] In step 1000, the fuel supply means switching means checks
if injection is performed by the gas mixture supply apparatus 21 or
main fuel injection valve 2. When the switching condition has been
established and injection by gas mixture supply apparatus 21 is
determined, control goes to step 1000. If injection by main fuel
injection valve 2 is determined, control goes to step 2000.
[0175] In step 2000, injection by main fuel injection valve 2 is
performed. In step 2100, the amount of injection by the gas mixture
supply apparatus 21 is reduced if injection by gas mixture supply
apparatus 21 has been performed in the previous routine. Then in
Step 2200, check is made to see if the starter is turned on or not.
If the starter is off, control goes to step 2300. If the starter is
evaluated as turned on in step 2200, setting is so made in step
that injection at the startup can be executed. Then control goes to
step 2300.
[0176] In step 2300, check is made to see if a predetermined state
of combustion has been reached or not. If the predetermined state
has been reached--e.g. engine speed has reached 800 r/min.--, then
the main fuel injection valve 2 is evaluated as normal in step
2400. If the predetermined state of combustion is not reached, the
routine is terminated immediately.
[0177] When injected by the gas mixture supply apparatus 21 is
determined in step 1000 and control has proceeded to step 1100,
check is made in step 1100 to see if the main fuel injection valve
2 is normal or not. If the main fuel injection valve 2 is not
evaluated as normal in step 1100, then the routine terminates
immediately. If the main fuel injection valve 2 is evaluated as
normal, control goes to step 1200.
[0178] In step 1300, injection by the gas mixture supply apparatus
21 is performed, and such control as turning on the heater (not
illustrated) is carried out at the same time. Then in step 1300,
injection of the main fuel injection valve 2 is stopped or the
volume of injection is gradually reduced to a value close to
zero.
[0179] In step 1400, delay angle of ignition timing is corrected,
and check is made to see if delay angle has been corrected to the
predetermined value in step 1500 or not. If the predetermined value
is not reached, the current routine is terminated immediately, and
this routine driven at every predetermined time interval is
repeated until it is reached.
[0180] When the delay angle has been correct ed to the
predetermined level, the range of the change in speed (.DELTA.N) is
calculated in step 1600. This calculation in step 1600 is detected
as the amount of change per unit time (e.g. 40 ms) during the
predetermined time which is measured from the time when the
aforementioned delay angle has been corrected to the predetermined
level.
[0181] In step 1700, check is made to see if the value of the
aforementioned .DELTA.N is greater than the preset value or not. If
this predetermined value is not reached, this routine is terminated
immediately. This routine driven at every predetermined time
interval is repeated. If this value has never been reached within
the specified time, the upstream injection valve is evaluated as
normal by another routine (not illustrated).
[0182] When the predetermined has been reached in step 1700, an
error of the gas mixture supply apparatus 21 is evaluated in step
1800, and the predetermined evaluation result flag is set. In step
1900, action is taken to interrupt the injection of the gas mixture
supply apparatus 21, correction of delay angle for ignition timing
and application of power to the heater. In step 1910, action is
further taken to disable injection of the gas mixture supply
apparatus 21 and correction of delay angle for ignition timing.
[0183] The above description has dealt with the gas mixture state
detecting means mainly for detecting the state of gas mixture and
the evaluation means for evaluation an error of the gas mixture
supply means. This means provides a method for diagnosing gas
mixture supply apparatus 21 for determining that the gas mixture
supply apparatus 21 has problem.
[0184] In addition to the aforementioned method of evaporation by
an electric heater for applying power to the heater member,
evaporation can be made by any of the following methods; heater
evaporation based on combustion heat, evaporation by ultrasonic
vibration, evaporation by hot water and evaporation by exhaust gas
temperature. They can be used except for the examples given in
FIGS. 17 to 19.
[0185] As described above, a diagnostic apparatus for gas mixture
supply apparatus and diagnostic method thereof in the present
embodiment is characterized in that;
[0186] in a gas mixture supply apparatus of an internal combustion
engine comprising;
[0187] a main fuel injection valve 2 for supplying fuel to an
internal combustion engine,
[0188] an upstream fuel injection valve 3 for supplying fuel to the
area upstream from the main fuel injection valve 2, and
[0189] gas mixture supply means for supplying gas mixture from
upstream of the main fuel injection valve 2 through an evaporation
means for evaporating all or part of fuel supplied from the
upstream fuel injection valve 3;
[0190] a diagnostic apparatus for the gas mixture supply apparatus
further comprising;
[0191] error evaluation means for detecting the state of gas
mixture being supplied, based on the result of detection such as
the amount of change in engine speed
[0192] and for evaluating an error of the gas mixture supply means
based on the result of detection such as the amount of change,
[0193] fail-safe control means containing;
[0194] a step of stopping the fuel supplied from upstream fuel
injection valve 3 when an error has been determined, and
[0195] a step of switching to the main fuel injection valve 2,
stopping of the evaporation means and correction of ignition timing
immediately or in a stepwise manner.
[0196] Thus, even if an error has occurred to the gas mixture
supply apparatus 21 and a sufficient amount of fuel cannot be
supplied, the present invention ensures engine startup, permits
continued operation of the engine without a problem which may cause
stalling of the engine, and prevents deterioration of exhaust gas.
This eliminates the following possible troubles which may occur
when a sufficient amount of evaporated fuel cannot be supplied from
the gas mixture supply apparatus due to an error of the gas mixture
supply means; failure in effective use of the advantage of
combustion improvement, increase in the amount of emitted
hydrocarbon and stalling of the engine due to combustion failure in
the worst case.
[0197] The above description has dealt with one embodiment of the
present invention. It should be apparent however, that various
design modifications of the present invention are possible without
the present invention being restricted only to the aforementioned
embodiments or without departing from the spirit of the present
invention as set forth in the claims.
[0198] As is apparent from the above description, a diagnostic
apparatus for gas mixture supply apparatus and diagnostic method
thereof according to the present invention provides a gas mixture
supply apparatus characterized in that, when any trouble has
occurred to a gas mixture supply apparatus, it can be identified as
an error; and at least engine startup can be ensured, continued
operation of the engine is enabled without any problem which may
cause stalling of the engine, and deterioration of exhaust gas can
be prevented.
* * * * *